Semiconductor device and method of manufacturing semiconductor device

Abstract

A semiconductor device, having: a substrate having a main surface with a recess; a device structure at the main surface; an interlayer insulating film covering the device structure; a contact hole penetrating through the interlayer insulating film to expose a portion of the device structure, the contact hole having a bottom configured by the recess; a barrier metal, including a titanium film provided along the side wall of the contact hole, and a titanium nitride film stacked on the titanium film and formed at the bottom of the contact hole; a titanium silicide film provided along an inner wall of the recess; a tungsten film provided on the barrier metal; and a metal electrode provided on the interlayer insulating film and the tungsten film. An upper surface of the titanium nitride film on the bottom of the contact hole is closer to the metal electrode than is the main surface.

What is claimed is: 
     
         1 . A semiconductor device, comprising:
 a semiconductor substrate having a main surface, the main surface having a recess formed therein;   a device structure provided at the main surface of the semiconductor substrate;   an interlayer insulating film provided on the main surface of the semiconductor substrate and covering the device structure;   a contact hole that, in a depth direction of the semiconductor device, penetrates through the interlayer insulating film to reach the main surface of the semiconductor substrate, thereby exposing a portion of the device structure, the contact hole having:
 a side wall, and 
 a bottom that is configured by the recess at the main surface of the semiconductor substrate; 
 a barrier metal, including 
 a titanium film provided along the side wall of the contact hole, and 
 a titanium nitride film that is stacked on the titanium film and formed on the bottom of the contact hole; 
   a titanium silicide film provided in the semiconductor substrate, along an inner wall of the recess of the semiconductor substrate;   a tungsten film provided in the contact hole, on the barrier metal; and   a metal electrode containing aluminum, provided on the interlayer insulating film and the tungsten film, wherein   in the depth direction of the semiconductor device, an upper surface of the titanium nitride film at the bottom of the contact hole is closer to the metal electrode than is the main surface of the semiconductor substrate.   
     
     
         2 . The semiconductor device according to  claim 1 , wherein in the depth direction of the semiconductor device, a distance between the main surface of the semiconductor substrate and the upper surface of the titanium nitride film at the bottom of the contact hole is 10 nm or more. 
     
     
         3 . The semiconductor device according to  claim 1 , wherein
 the titanium nitride film has an indentation formed at the upper surface thereof in a bottom corner of the contact hole.   
     
     
         4 . A method of manufacturing a semiconductor device, the method comprising:
 preparing a semiconductor substrate having a main surface;   forming a device structure at the main surface of the semiconductor substrate;   forming an interlayer insulating film on the main surface of the semiconductor substrate, the interlayer insulating film covering the device structure;   forming a contact hole from an upper surface of the interlayer insulating film, to penetrate through the interlayer insulating film in a depth direction of the semiconductor device and to form a recess at the main surface of the semiconductor substrate, the contact hole exposing a portion of the device structure, and having:
 a side wall, and 
 a bottom that is configured by the recess at the main surface of the semiconductor substrate; 
   sequentially forming a titanium film and a titanium nitride film, as a barrier metal, along an inner wall of the contact hole;   performing a heat treatment thereby causing the titanium film at the bottom of the contact hole and the semiconductor substrate to react with each other, thereby forming a titanium silicide film in the semiconductor substrate along an inner wall of the recess;   performing a chemical vapor deposition thereby depositing a tungsten film on the barrier metal in the contact hole, thereby embedding the tungsten film in the contact hole; and   forming a metal electrode containing aluminum, on the interlayer insulating film and the tungsten film, wherein   after the heat treatment, in the depth direction of the semiconductor device, an upper surface of the titanium nitride film at the bottom of the contact hole is closer to the interlayer insulating film than is the main surface of the semiconductor substrate.   
     
     
         5 . The method of manufacturing according to  claim 4 , wherein
 forming the titanium nitride film includes depositing the titanium nitride film having a thickness obtained by adding, to a thickness of the titanium nitride film as the barrier metal, a distance that the titanium nitride film moves in the depth direction when the titanium nitride film sinks due to the heat treatment.   
     
     
         6 . The method of manufacturing according to  claim 5 , wherein
 after forming the titanium silicide film, in the depth direction of the semiconductor device, a distance between the main surface of the semiconductor substrate and the upper surface of the titanium nitride film at the bottom of the contact hole is 10 nm or more.   
     
     
         7 . The method of manufacturing according to  claim 4 , wherein
 the recess at the main surface of the semiconductor substrate has a depth that is less than a thickness of the titanium nitride film deposited at the bottom of the contact hole in the depth direction of the semiconductor device.   
     
     
         8 . The method of manufacturing according to  claim 4 , wherein
 the recess at the main surface of the semiconductor substrate has a depth that is less than a combined thickness of
 a thickness of the titanium nitride film deposited at the bottom of the contact hole, and 
 a thickness of the titanium film left unreacted with the 
   semiconductor substrate at the bottom of the contact hole, in the depth direction of the semiconductor device.